Due to the HTML structure of Marketers Delight, each article is wrapped in an <article> tag, which specifies each one of them as its own individual self-contained piece of content on the page. 11.
tag definition from W3 Schools. ×

Because each article acts as a separate entity from the rest of the page, and to avoid validation errors, we need to feed it meta data that it wouldn’t pull from the page it’s listed on. One important piece of data is the Publisher Logo.

Google added Publisher Logos to Markup Schema for compatibility with the new AMP program, which helps deliver faster web pages on mobile. The logo you set as your Publisher Logo will be pulled for use on AMP pages and will tell Google your preferred logo for use in search results. 22.
From the Google Webmaster Blog, ×

Adding a Schema Publisher Logo to Marketers Delight

There are various Publisher properties associated with Schema, and Marketers Delight 4.4.2 adds the properties you need to validate into every post for you. However, if you don’t have a publisher logo uploaded, you will get a validation error.

Because of the AMP logo requirements, your current site’s logo may not fit the requirements for the recommended Publisher Logo. That’s why MD4.4.2 added the new Site Tools panel with the Schema Logo Upload field so you can upload a modified version of your site’s logo for use by Google.